A variety of spinal injuries and deformities can occur due to trauma, disease or congenital effects. For example, one type of spinal deformity, a kyphosis, involves a prolapse of the vertebral column towards the front of the body, often caused by the destruction of the vertebral body itself. This destruction can be in the form of a trauma type injury, such as a fracture or burst injury to the vertebral body, or a non-traumatic deformity caused by a tumor or a degeneration of the bone in the vertebral body.
Treatment of a kyphosis in the thoracic or lumbar spine appears now to be best achieved through an anterior approach, particularly in order to avoid some of the more severe complications associated with support or replacement of a damaged vertebral body. In most treatments of a kyphosis, a high degree of anterior reconstruction of the spine is required, most frequently involving total removal of the damaged vertebral body. In a typical anterior approach, partial or total ablation of the vertebral body and the two adjacent vertebral discs is carried out. Following this vertebrectomy, a vertebral implant assembly may be used to restore the vertebral column to the correct orientation.
One implant that may be used is disclosed in U.S. Pat. No. 6,344,057 to Rabbe et al. (“Rabbe patent”), which is hereby incorporated by reference. The implant disclosed in the Rabbe patent is an adjustable vertebral implant assembly configured to span the void created by the removed vertebral body and discs. The assembly includes a thin-walled tubular body which defines a hollow interior and further includes endplates with end surfaces configured to engage the tubular body between the adjacent vertebrae. In some embodiments, the end surfaces defines a bore through the endplate.
Current surgical spinal reconstruction techniques can use a plurality of wrenches to expand or otherwise manipulate rotationally adjustable implants, such as the assembly disclosed in the Rabbe patent. However, a wrench requires lateral translation which, in the confined area of the wound, can require an enlarged wound and increased labor and time. It must also relocate and reattach to the implant after each turn, which is both difficult and time consuming.